1 Wash the lettuce, drain-well, tear the leaves into pieces.
2 Heat the butter in a saucepan, add the lettuce pieces, shelled peas, salt and sugar. Cover the pan, reduce the heat and let the vegetables cook gently over low heat for about 10 minutes. Stir in the stock, cover and simmer 10 minutes more or until the peas are tender.
3 Puree the soup by rubbing through a strainer or puree in a blender. Return the pea puree to a clean saucepan, add black pepper to taste and heat again until just simmering. Serve at once.